9.2.1.3 Application Curves

-1

0

1

2

3

4

0

50

100

150

200

250

300

350

400

450

500

Time (ns)

Input

Output

.

Figure 9-4. Captured Waveform From Above I2C

Set-Up (1.8 V to 3.3 V at 2.5 MHz)

Input (3.3V)

Output (1.0V)

.

Figure 9-5. Captured Waveform From Above MDIO

Setup

9.2.2 Mixed-Mode Voltage Translation

The supply voltage (Vpu#) for each channel can be individually set with a pull-up resistor. Figure 9-6 shows an

example of this mixed-mode multi-voltage translation. For additional details on multi-voltage translation, see the

Multi-voltage Translation with the LSF Family video.

With the Vref_B pulled up to 5 V and Vref_A connected to 1.8 V, all channels will be clamped to 1.8 V at which

point a pullup can be used to define the high level voltage for a given channel.

• Push-Pull Down Translation (5 V to 1.8 V): Channel 1 is an example of this setup. When B1 is 5 V, A1 is

clamped to 1.8 V, and when B1 is LOW, A1 is driven LOW through the switch.

• Push-Pull Up Translation (1.8 V to 5 V): Channel 2 is an example of this setup. When A2 is 1.8 V, the

switch is high impedance and the B2 channel is pulled up to 5 V. When A2 is LOW, B2 is driven LOW through

the switch.

• Push-Pull Down Translation (3.3 V to 1.8 V): Channels 3 and 4 are examples of this setup. When either B3

or B4 are driven to 3.3 V, A3 or A4 are clamped to 1.8 V, and when either B3 or B4 are LOW, A3 or A4 are

driven LOW through the switch.

• Open-Drain Bidirectional Translation (3.3 V ↔ 1.8 V): Channels 5 through 8 are examples of this setup.

These channels are for bidirectional operation for I2C and MDIO to translate between 1.8 V and 3.3 V with

open-drain drivers.

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LSF0108-Q1

SDLS967E – MAY 2016 – REVISED NOVEMBER 2022

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